99 sonoma fuel issue

I have a 99 sonoma with a 4.3 v6 and 180,000 miles on it. The truck starts then dies one to five seconds later. When I depress the foot throttle the truck dies instantly. I think I have finally narrowed down to the fuel system because i put fuel in the intake and it ran for 30 seconds. The pressure is at 60 psi and drops to about 56 after the truck dies so I don't think its a leak or the fuel pump. Any help is appreciated.